fix(fusion_helpdesk): auto-grant reporter admin to system admins + doc backfill

The customer-followup ship left two papercuts that hid 51 historical
tickets from the entech owner:

1. group_reporter_admin had zero members on install — the new XML record
   created the group but never granted it. Extend base.group_system's
   implied_ids so every system administrator transparently inherits the
   admin view of the embedded inbox on install / upgrade. (4, id) tuple
   is additive — never replaces base's existing implications.

2. Tickets created before this feature shipped had NULL
   x_fc_client_label and NULL partner_email, so the scope filter
   excluded them all. The reporter identity was still recoverable from
   the description HTML's diag block. Backfill recipe is captured in
   CLAUDE.md so future deployments can apply the same one-shot UPDATE
   without re-deriving the regex.

Bumps fusion_helpdesk to 19.0.1.5.0. Verified live on entech: all six
base.group_system members now return True for
has_group('fusion_helpdesk.group_reporter_admin').

fusion_helpdesk/__manifest__.py

@@ -3,7 +3,7 @@
 # License OPL-1 (Odoo Proprietary License v1.0)
 {
     'name': 'Fusion Helpdesk Reporter',
-    'version': '19.0.1.4.1',
+    'version': '19.0.1.5.0',
     'category': 'Productivity',
     'summary': 'One-click in-app bug reporting & feature requesting — '
                'auto-creates a helpdesk.ticket on a central Odoo Helpdesk.',